﻿/* 7zCrc.c -- CRC32 init
2021-04-01 : Igor Pavlov : Public domain */

#include "Precomp.h"

#include "7zCrc.h"
#include "CpuArch.h"

#define kCrcPoly 0xEDB88320

#ifdef MY_CPU_LE
  #define CRC_NUM_TABLES 8
#else
  #define CRC_NUM_TABLES 9

  #define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24))

  UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
  UInt32 MY_FAST_CALL CrcUpdateT1_BeT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
#endif

#ifndef MY_CPU_BE
  UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
  UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
#endif

typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);

extern
CRC_FUNC g_CrcUpdateT4;
CRC_FUNC g_CrcUpdateT4;
extern
CRC_FUNC g_CrcUpdateT8;
CRC_FUNC g_CrcUpdateT8;
extern
CRC_FUNC g_CrcUpdateT0_32;
CRC_FUNC g_CrcUpdateT0_32;
extern
CRC_FUNC g_CrcUpdateT0_64;
CRC_FUNC g_CrcUpdateT0_64;
extern
CRC_FUNC g_CrcUpdate;
CRC_FUNC g_CrcUpdate;

UInt32 g_CrcTable[256 * CRC_NUM_TABLES];

UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
{
  return g_CrcUpdate(v, data, size, g_CrcTable);
}

UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
{
  return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;
}

#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))

UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table);
UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table)
{
  const Byte *p = (const Byte *)data;
  const Byte *pEnd = p + size;
  for (; p != pEnd; p++)
    v = CRC_UPDATE_BYTE_2(v, *p);
  return v;
}


/* ---------- hardware CRC ---------- */

#ifdef MY_CPU_LE

#if defined(MY_CPU_ARM_OR_ARM64)

// #pragma message("ARM*")

  #if defined(_MSC_VER)
    #if defined(MY_CPU_ARM64)
    #if (_MSC_VER >= 1910)
        #define USE_ARM64_CRC
    #endif
    #endif
  #elif (defined(__clang__) && (__clang_major__ >= 3)) \
     || (defined(__GNUC__) && (__GNUC__ > 4))
      #if !defined(__ARM_FEATURE_CRC32)
        #define __ARM_FEATURE_CRC32 1
          #if (!defined(__clang__) || (__clang_major__ > 3)) // fix these numbers
            #define ATTRIB_CRC __attribute__((__target__("arch=armv8-a+crc")))
          #endif
      #endif
      #if defined(__ARM_FEATURE_CRC32)
        #define USE_ARM64_CRC
        #include <arm_acle.h>
      #endif
  #endif

#else

// no hardware CRC

// #define USE_CRC_EMU

#ifdef USE_CRC_EMU

#pragma message("ARM64 CRC emulation")

MY_FORCE_INLINE
UInt32 __crc32b(UInt32 v, UInt32 data)
{
  const UInt32 *table = g_CrcTable;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data);
  return v;
}

MY_FORCE_INLINE
UInt32 __crc32w(UInt32 v, UInt32 data)
{
  const UInt32 *table = g_CrcTable;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  return v;
}

MY_FORCE_INLINE
UInt32 __crc32d(UInt32 v, UInt64 data)
{
  const UInt32 *table = g_CrcTable;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  v = CRC_UPDATE_BYTE_2(v, (Byte)data); data >>= 8;
  return v;
}

#endif // USE_CRC_EMU

#endif // defined(MY_CPU_ARM64) && defined(MY_CPU_LE)



#if defined(USE_ARM64_CRC) || defined(USE_CRC_EMU)

#define T0_32_UNROLL_BYTES (4 * 4)
#define T0_64_UNROLL_BYTES (4 * 8)

#ifndef ATTRIB_CRC
#define ATTRIB_CRC
#endif
// #pragma message("USE ARM HW CRC")

ATTRIB_CRC
UInt32 MY_FAST_CALL CrcUpdateT0_32(UInt32 v, const void *data, size_t size, const UInt32 *table);
ATTRIB_CRC
UInt32 MY_FAST_CALL CrcUpdateT0_32(UInt32 v, const void *data, size_t size, const UInt32 *table)
{
  const Byte *p = (const Byte *)data;
  UNUSED_VAR(table);

  for (; size != 0 && ((unsigned)(ptrdiff_t)p & (T0_32_UNROLL_BYTES - 1)) != 0; size--)
    v = __crc32b(v, *p++);

  if (size >= T0_32_UNROLL_BYTES)
  {
    const Byte *lim = p + size;
    size &= (T0_32_UNROLL_BYTES - 1);
    lim -= size;
    do
    {
      v = __crc32w(v, *(const UInt32 *)(const void *)(p));
      v = __crc32w(v, *(const UInt32 *)(const void *)(p + 4)); p += 2 * 4;
      v = __crc32w(v, *(const UInt32 *)(const void *)(p));
      v = __crc32w(v, *(const UInt32 *)(const void *)(p + 4)); p += 2 * 4;
    }
    while (p != lim);
  }
  
  for (; size != 0; size--)
    v = __crc32b(v, *p++);

  return v;
}

ATTRIB_CRC
UInt32 MY_FAST_CALL CrcUpdateT0_64(UInt32 v, const void *data, size_t size, const UInt32 *table);
ATTRIB_CRC
UInt32 MY_FAST_CALL CrcUpdateT0_64(UInt32 v, const void *data, size_t size, const UInt32 *table)
{
  const Byte *p = (const Byte *)data;
  UNUSED_VAR(table);

  for (; size != 0 && ((unsigned)(ptrdiff_t)p & (T0_64_UNROLL_BYTES - 1)) != 0; size--)
    v = __crc32b(v, *p++);

  if (size >= T0_64_UNROLL_BYTES)
  {
    const Byte *lim = p + size;
    size &= (T0_64_UNROLL_BYTES - 1);
    lim -= size;
    do
    {
      v = __crc32d(v, *(const UInt64 *)(const void *)(p));
      v = __crc32d(v, *(const UInt64 *)(const void *)(p + 8)); p += 2 * 8;
      v = __crc32d(v, *(const UInt64 *)(const void *)(p));
      v = __crc32d(v, *(const UInt64 *)(const void *)(p + 8)); p += 2 * 8;
    }
    while (p != lim);
  }
  
  for (; size != 0; size--)
    v = __crc32b(v, *p++);

  return v;
}

#endif // defined(USE_ARM64_CRC) || defined(USE_CRC_EMU)

#endif // MY_CPU_LE




void MY_FAST_CALL CrcGenerateTable()
{
  UInt32 i;
  for (i = 0; i < 256; i++)
  {
    UInt32 r = i;
    unsigned j;
    for (j = 0; j < 8; j++)
      r = (r >> 1) ^ (kCrcPoly & ((UInt32)0 - (r & 1)));
    g_CrcTable[i] = r;
  }
  for (i = 256; i < 256 * CRC_NUM_TABLES; i++)
  {
    UInt32 r = g_CrcTable[(size_t)i - 256];
    g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
  }

  #if CRC_NUM_TABLES < 4
  
  g_CrcUpdate = CrcUpdateT1;
  
  #else
 
  #ifdef MY_CPU_LE

    g_CrcUpdateT4 = CrcUpdateT4;
    g_CrcUpdate = CrcUpdateT4;

    #if CRC_NUM_TABLES >= 8
      g_CrcUpdateT8 = CrcUpdateT8;
  
      #ifdef MY_CPU_X86_OR_AMD64
      if (!CPU_Is_InOrder())
      #endif
        g_CrcUpdate = CrcUpdateT8;
    #endif

  #else
  {
    #ifndef MY_CPU_BE
    UInt32 k = 0x01020304;
    const Byte *p = (const Byte *)&k;
    if (p[0] == 4 && p[1] == 3)
    {
      g_CrcUpdateT4 = CrcUpdateT4;
      g_CrcUpdate = CrcUpdateT4;
      #if CRC_NUM_TABLES >= 8
      g_CrcUpdateT8 = CrcUpdateT8;
      g_CrcUpdate = CrcUpdateT8;
      #endif
    }
    else if (p[0] != 1 || p[1] != 2)
      g_CrcUpdate = CrcUpdateT1;
    else
    #endif
    {
      for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--)
      {
        UInt32 x = g_CrcTable[(size_t)i - 256];
        g_CrcTable[i] = CRC_UINT32_SWAP(x);
      }
      g_CrcUpdateT4 = CrcUpdateT1_BeT4;
      g_CrcUpdate = CrcUpdateT1_BeT4;
      #if CRC_NUM_TABLES >= 8
      g_CrcUpdateT8 = CrcUpdateT1_BeT8;
      g_CrcUpdate = CrcUpdateT1_BeT8;
      #endif
    }
  }
  #endif
  #endif

  #ifdef MY_CPU_LE
    #ifdef USE_ARM64_CRC
      if (CPU_IsSupported_CRC32())
      {
        g_CrcUpdateT0_32 = CrcUpdateT0_32;
        g_CrcUpdateT0_64 = CrcUpdateT0_64;
        g_CrcUpdate =
          #if defined(MY_CPU_ARM)
            CrcUpdateT0_32;
          #else
            CrcUpdateT0_64;
          #endif
      }
    #endif
    
    #ifdef USE_CRC_EMU
      g_CrcUpdateT0_32 = CrcUpdateT0_32;
      g_CrcUpdateT0_64 = CrcUpdateT0_64;
      g_CrcUpdate = CrcUpdateT0_64;
    #endif
  #endif
}
